UPDATE: changed the buffer tube; since it was my first time, I had the help of some YouTube videos.
Went to the range last Friday and was able to shoot 55-grain FMJ's without a single misfire, as well as 60-grain Nosler Partitions and 70-grain Barnes TSX's. Seems I'm in great shape for deer season---and any day I just want to burn through a few boxes of cheap stuff!
Loving this rifle.